1 /* 2 * drivers/char/watchdog/max63xx_wdt.c 3 * 4 * Driver for max63{69,70,71,72,73,74} watchdog timers 5 * 6 * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org> 7 * 8 * This file is licensed under the terms of the GNU General Public 9 * License version 2. This program is licensed "as is" without any 10 * warranty of any kind, whether express or implied. 11 * 12 * This driver assumes the watchdog pins are memory mapped (as it is 13 * the case for the Arcom Zeus). Should it be connected over GPIOs or 14 * another interface, some abstraction will have to be introduced. 15 */ 16 17 #include <linux/err.h> 18 #include <linux/module.h> 19 #include <linux/moduleparam.h> 20 #include <linux/mod_devicetable.h> 21 #include <linux/types.h> 22 #include <linux/kernel.h> 23 #include <linux/watchdog.h> 24 #include <linux/bitops.h> 25 #include <linux/platform_device.h> 26 #include <linux/spinlock.h> 27 #include <linux/io.h> 28 #include <linux/slab.h> 29 #include <linux/property.h> 30 31 #define DEFAULT_HEARTBEAT 60 32 #define MAX_HEARTBEAT 60 33 34 static unsigned int heartbeat = DEFAULT_HEARTBEAT; 35 static bool nowayout = WATCHDOG_NOWAYOUT; 36 37 /* 38 * Memory mapping: a single byte, 3 first lower bits to select bit 3 39 * to ping the watchdog. 40 */ 41 #define MAX6369_WDSET (7 << 0) 42 #define MAX6369_WDI (1 << 3) 43 44 #define MAX6369_WDSET_DISABLED 3 45 46 static int nodelay; 47 48 struct max63xx_wdt { 49 struct watchdog_device wdd; 50 const struct max63xx_timeout *timeout; 51 52 /* memory mapping */ 53 void __iomem *base; 54 spinlock_t lock; 55 56 /* WDI and WSET bits write access routines */ 57 void (*ping)(struct max63xx_wdt *wdt); 58 void (*set)(struct max63xx_wdt *wdt, u8 set); 59 }; 60 61 /* 62 * The timeout values used are actually the absolute minimum the chip 63 * offers. Typical values on my board are slightly over twice as long 64 * (10s setting ends up with a 25s timeout), and can be up to 3 times 65 * the nominal setting (according to the datasheet). So please take 66 * these values with a grain of salt. Same goes for the initial delay 67 * "feature". Only max6373/74 have a few settings without this initial 68 * delay (selected with the "nodelay" parameter). 69 * 70 * I also decided to remove from the tables any timeout smaller than a 71 * second, as it looked completly overkill... 72 */ 73 74 /* Timeouts in second */ 75 struct max63xx_timeout { 76 const u8 wdset; 77 const u8 tdelay; 78 const u8 twd; 79 }; 80 81 static const struct max63xx_timeout max6369_table[] = { 82 { 5, 1, 1 }, 83 { 6, 10, 10 }, 84 { 7, 60, 60 }, 85 { }, 86 }; 87 88 static const struct max63xx_timeout max6371_table[] = { 89 { 6, 60, 3 }, 90 { 7, 60, 60 }, 91 { }, 92 }; 93 94 static const struct max63xx_timeout max6373_table[] = { 95 { 2, 60, 1 }, 96 { 5, 0, 1 }, 97 { 1, 3, 3 }, 98 { 7, 60, 10 }, 99 { 6, 0, 10 }, 100 { }, 101 }; 102 103 static const struct max63xx_timeout * 104 max63xx_select_timeout(const struct max63xx_timeout *table, int value) 105 { 106 while (table->twd) { 107 if (value <= table->twd) { 108 if (nodelay && table->tdelay == 0) 109 return table; 110 111 if (!nodelay) 112 return table; 113 } 114 115 table++; 116 } 117 118 return NULL; 119 } 120 121 static int max63xx_wdt_ping(struct watchdog_device *wdd) 122 { 123 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd); 124 125 wdt->ping(wdt); 126 return 0; 127 } 128 129 static int max63xx_wdt_start(struct watchdog_device *wdd) 130 { 131 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd); 132 133 wdt->set(wdt, wdt->timeout->wdset); 134 135 /* check for a edge triggered startup */ 136 if (wdt->timeout->tdelay == 0) 137 wdt->ping(wdt); 138 return 0; 139 } 140 141 static int max63xx_wdt_stop(struct watchdog_device *wdd) 142 { 143 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd); 144 145 wdt->set(wdt, MAX6369_WDSET_DISABLED); 146 return 0; 147 } 148 149 static const struct watchdog_ops max63xx_wdt_ops = { 150 .owner = THIS_MODULE, 151 .start = max63xx_wdt_start, 152 .stop = max63xx_wdt_stop, 153 .ping = max63xx_wdt_ping, 154 }; 155 156 static const struct watchdog_info max63xx_wdt_info = { 157 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE, 158 .identity = "max63xx Watchdog", 159 }; 160 161 static void max63xx_mmap_ping(struct max63xx_wdt *wdt) 162 { 163 u8 val; 164 165 spin_lock(&wdt->lock); 166 167 val = __raw_readb(wdt->base); 168 169 __raw_writeb(val | MAX6369_WDI, wdt->base); 170 __raw_writeb(val & ~MAX6369_WDI, wdt->base); 171 172 spin_unlock(&wdt->lock); 173 } 174 175 static void max63xx_mmap_set(struct max63xx_wdt *wdt, u8 set) 176 { 177 u8 val; 178 179 spin_lock(&wdt->lock); 180 181 val = __raw_readb(wdt->base); 182 val &= ~MAX6369_WDSET; 183 val |= set & MAX6369_WDSET; 184 __raw_writeb(val, wdt->base); 185 186 spin_unlock(&wdt->lock); 187 } 188 189 static int max63xx_mmap_init(struct platform_device *p, struct max63xx_wdt *wdt) 190 { 191 wdt->base = devm_platform_ioremap_resource(p, 0); 192 if (IS_ERR(wdt->base)) 193 return PTR_ERR(wdt->base); 194 195 spin_lock_init(&wdt->lock); 196 197 wdt->ping = max63xx_mmap_ping; 198 wdt->set = max63xx_mmap_set; 199 return 0; 200 } 201 202 static int max63xx_wdt_probe(struct platform_device *pdev) 203 { 204 struct device *dev = &pdev->dev; 205 struct max63xx_wdt *wdt; 206 const struct max63xx_timeout *table; 207 int err; 208 209 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); 210 if (!wdt) 211 return -ENOMEM; 212 213 /* Attempt to use fwnode first */ 214 table = device_get_match_data(dev); 215 if (!table) 216 table = (struct max63xx_timeout *)pdev->id_entry->driver_data; 217 218 if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT) 219 heartbeat = DEFAULT_HEARTBEAT; 220 221 wdt->timeout = max63xx_select_timeout(table, heartbeat); 222 if (!wdt->timeout) { 223 dev_err(dev, "unable to satisfy %ds heartbeat request\n", 224 heartbeat); 225 return -EINVAL; 226 } 227 228 err = max63xx_mmap_init(pdev, wdt); 229 if (err) 230 return err; 231 232 platform_set_drvdata(pdev, &wdt->wdd); 233 watchdog_set_drvdata(&wdt->wdd, wdt); 234 235 wdt->wdd.parent = dev; 236 wdt->wdd.timeout = wdt->timeout->twd; 237 wdt->wdd.info = &max63xx_wdt_info; 238 wdt->wdd.ops = &max63xx_wdt_ops; 239 240 watchdog_set_nowayout(&wdt->wdd, nowayout); 241 242 err = devm_watchdog_register_device(dev, &wdt->wdd); 243 if (err) 244 return err; 245 246 dev_info(dev, "using %ds heartbeat with %ds initial delay\n", 247 wdt->timeout->twd, wdt->timeout->tdelay); 248 return 0; 249 } 250 251 static const struct platform_device_id max63xx_id_table[] = { 252 { "max6369_wdt", (kernel_ulong_t)max6369_table, }, 253 { "max6370_wdt", (kernel_ulong_t)max6369_table, }, 254 { "max6371_wdt", (kernel_ulong_t)max6371_table, }, 255 { "max6372_wdt", (kernel_ulong_t)max6371_table, }, 256 { "max6373_wdt", (kernel_ulong_t)max6373_table, }, 257 { "max6374_wdt", (kernel_ulong_t)max6373_table, }, 258 { }, 259 }; 260 MODULE_DEVICE_TABLE(platform, max63xx_id_table); 261 262 static const struct of_device_id max63xx_dt_id_table[] = { 263 { .compatible = "maxim,max6369", .data = max6369_table, }, 264 { .compatible = "maxim,max6370", .data = max6369_table, }, 265 { .compatible = "maxim,max6371", .data = max6371_table, }, 266 { .compatible = "maxim,max6372", .data = max6371_table, }, 267 { .compatible = "maxim,max6373", .data = max6373_table, }, 268 { .compatible = "maxim,max6374", .data = max6373_table, }, 269 { } 270 }; 271 MODULE_DEVICE_TABLE(of, max63xx_dt_id_table); 272 273 static struct platform_driver max63xx_wdt_driver = { 274 .probe = max63xx_wdt_probe, 275 .id_table = max63xx_id_table, 276 .driver = { 277 .name = "max63xx_wdt", 278 .of_match_table = max63xx_dt_id_table, 279 }, 280 }; 281 282 module_platform_driver(max63xx_wdt_driver); 283 284 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>"); 285 MODULE_DESCRIPTION("max63xx Watchdog Driver"); 286 287 module_param(heartbeat, int, 0); 288 MODULE_PARM_DESC(heartbeat, 289 "Watchdog heartbeat period in seconds from 1 to " 290 __MODULE_STRING(MAX_HEARTBEAT) ", default " 291 __MODULE_STRING(DEFAULT_HEARTBEAT)); 292 293 module_param(nowayout, bool, 0); 294 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" 295 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); 296 297 module_param(nodelay, int, 0); 298 MODULE_PARM_DESC(nodelay, 299 "Force selection of a timeout setting without initial delay " 300 "(max6373/74 only, default=0)"); 301 302 MODULE_LICENSE("GPL v2"); 303